1. Field of the Invention
The present invention relates to an accumulating system and a method for processing abnormality of an accumulating system, and particularly to a technique for controlling an accumulating system when abnormality of an accumulator battery is detected.
2. Description of the Background Art
Japanese Patent Laying-Open No. 05-236662 discloses a charging system for lead-acid batteries. This charging system measures a voltage of each block constituting the batteries. A difference in an average voltage per one cell between the blocks reaching at least a prescribed voltage is determined to be an indication of abnormality, upon which charging is stopped.
According to the charging system, upon occurrence of an abnormal cell that is involved with disconnection between the cells, internal short-circuiting and the like in each block, a block with the abnormal cell can accurately be determined to stop charging.
Japanese Patent Laying-Open No. 2000-357541 discloses a battery management device for managing the charging/discharging state of a battery as appropriate when there is a trouble in a detection system of a battery electromotive voltage. The battery management device suppresses a charging/discharging current of a battery when a trouble of a voltage detector detecting an electromotive voltage of the battery is sensed.
According to the battery management device, a fail-safe when there is a trouble with the voltage detector can be implemented.
In the charging system disclosed in Japanese Patent Laying-Open No. 05-236662, charging to the accumulator battery is stopped upon detection of an abnormal cell. Specifically, charging to the accumulator battery is stopped even in a situation of minor short-circuiting abnormality where some of the numerous cells constituting the accumulator battery are involved with short-circuiting while the accumulator battery as a whole is still capable of charging/discharging. Accordingly, the charging system greatly affects a load using the accumulator battery.
In order to address such a situation of minor short-circuiting abnormality, for example it may be possible to actuate a cooling fan of the accumulator battery and to output an alert by turning on a lamp, and not to stop charging/discharging of the accumulator battery.
However, if the accumulator battery is continued to be used in the situation of minor short-circuiting abnormality, the abnormal cell may be overheated in accordance with an increase in the internal resistance thereof, whereby the accumulator battery may be broken. In particular, a hybrid vehicle or an electric vehicle that is receiving great attention recent years frequently conducts charging/discharging of a large current in an accumulator battery incorporated as a motive power source. Therefore, if the accumulator battery is continuously used in the situation of minor short-circuiting abnormality, the abnormal cell may abruptly be overheated. Therefore, as to a hybrid vehicle or the like, it is required not to stop charging/discharging of the accumulator battery in consideration of the effect on the system in the situation of minor short-circuiting abnormality, but still to surely prevent the accumulator battery from breaking due to an abruptly overheated cell.
Meanwhile, the battery management device disclosed in Japanese Patent Laying-Open No. 2000-357541 suppresses a charging/discharging current without stopping charging/discharging of an accumulator battery when a trouble of a voltage detector is sensed. However, upon sensing the trouble of the voltage detector, the battery management device employs a charging/discharging current control value Ic′ that is suppressed as compared to a normal charging/discharging current control value Ic to exert charging/discharging control. Thus, the charging/discharging current is suppressed irrespective of the input/output state of the accumulator battery. Accordingly, the effect on a load using the accumulator battery is not always small.